This invention relates to a ski structure, and more specifically, it is concerned with the impact absorbing edges used in conjunction with elastomeric sidewalls used on alpine skis to maximize snow surface contact by the bottom edges of the skis.
The continued popularity of downhill skiing has focused attention on the structure of skis to produce a ski that provides greater responsiveness to the improved skiing techniques being employed by skiers today and the increased speed being achieved as a result of these techniques. Attempting to maintain this continued popularity, the materials used in skis have been changed to develop higher performance skis with lower manufacturing costs. Higher performance levels are especially important to alpine skiers when carving turns at high speeds. This is primarily a factor with racers and advanced skiers where constant control of the skis at high speeds is essential.
High speed skiing requires that the ski, and more particularly the bottom ski edges, remain in contact with the snow surface, especially during turns. It has previously been felt that vibration within the skis must be controlled to increase the hold of the ski edges on ice and snow and to reduce "chatter" in the skis, that is, the loss of contact with the snow-covered ground as the skis move across. Loss of contact of the edges with the snow can cause the ski to slide laterally with respect to the fall line in turns.
One approach to controlling ski vibration deals with dampening the vibrational energy in the skis. Vibrations are created in all skis as they slide across smooth snow-covered ground, the vibrational energy level increasing with greater unevenness of the ground. The natural vibration frequency of skis is relatively low, but the forced vibration frequency of skis traveling over uneven surfaces is quite high. Vibration dampening in ranges covering 50 to 100 cycles per second (cps) and 100 to 300 cps has been commercially employed recently in attempts to prevent the build up of energy within the ski sufficient to cause the ski edges to release contact with the snow-covered ground. This release is believed to be caused by ski contact with the snow-covered ground which creates forced vibrations approaching harmonic frequencies within the ski.
Previous attempts or approaches to dampening the vibration in laminate or multi-layered snow skis have included the use of internal rubber layers and layers of viscoelastic material within the ski and on the top surface of the ski, the latter in combination with a stretch resistant constraining layer. However, all of these approaches either add significantly to the cost of the ski, increase the weight of the ski, and/or reduce the responsiveness and rate of return of the ski.
Another approach to controlling the vibrations in skis maintains that the longitudinal deflection of the ski, not vibration, is the predominant factor which causes the ski edges to release their contact with the snow surface. If the external force or forced deflection can be controlled, it is felt that the ski "chattering" can be controlled. If the impacts from the ground or snow surface to the ski edges are not absorbed by the ski structure, structural vibrations within the ski will commence and the edges will release contact with the snow-covered surface.
The foregoing problems are solved in the design of the present invention by providing an alpine ski structure which uses elastomeric sidewalls in the skis to permit the bottom edges of the ski to flex to absorb external forces while conforming to the shape of the snow-covered ground.